1. Field of Invention
The present invention relates generally to lighting devices for motor vehicles and, more specifically, to a lighting device with an optical fiber having a coupling lens and a transport and conversion lens.
2. Description of Related Art
Motor vehicle lighting devices known in the art typically include a light source and have having an optical waveguide. The optical waveguide has a first side, a second side lying opposite the first side, and narrow sides lying between an edge of the first side and an edge of the second side, and connecting the first side to the second side. The optical waveguide also has a coupling lens that couples and transforms the light from the light source, wherein the coupling lens has at least one reflector which transforms light emitted from the light source in a solid angle. Further, the optical waveguide has imaginary first planes and second planes, which are defined in that the first and second planes are perpendicular to one another, and intersect, wherein the lines of intersection are each defined by a light beam emitted from the reflector. A lighting device of this type is known from Published German Patent Application DE 19925363 A1.
In order to obtain a parallel light diffusion in the optical waveguide in the direction toward the light emission surface, the known lighting device provides that the narrow side of the plate-shaped optical waveguide lying opposite the band-shaped light emission side is designed as a reflector, which has parabolic contours in the first planes, thus in the planes parallel to the extended plate surfaces, and the plane perpendicular thereto has a prismatic contour, which deflects the light striking it twice. As a result, the reflector deflects light striking it at an aperture angle as parallel light onto the band-shaped light emission surface lying opposite the reflector.
A major disadvantage of this optical waveguide is that light emitted radially, directly into the half space facing the light emission surface, does not reach the reflector, and for this reason, is not parallelized. For use in lighting devices for motor vehicles, whether this is for headlamp functions or for signal light functions, however, a light emission surface is desired that is illuminated by light that is parallel and homogenous (uniformly bright) to the greatest extent possible. Light of this type has, for example, the advantage that it can be particularly easily distributed in light distributions conforming to government-mandated regulations with lenses disposed downstream and/or in the light emission surface. From the perspective of the design, moreover, an optical waveguide is desired, having a band-shaped light emission surface with a large ratio for the length of the light emission surface to its width, and which fulfills these requirements regarding homogeneity and parallelity.
Based on this background, the object of the invention is to provide a lighting device having an optical waveguide, which has a band-shaped light emission surface, which is homogenously illuminated by light that is parallel to the greatest extent possible, and which can be produced easily, and in a large number of variations, and can be adapted to various designs for motor vehicle lighting devices, which differ, for example, in terms of the available installation space.